ASTM D198-2013 Standard Test Methods of Static Tests of Lumber in Structural Sizes《结构尺寸木料静力学试验的标准试验方法》.pdf

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1、Designation: D198 09D198 13Standard Test Methods ofStatic Tests of Lumber in Structural Sizes1This standard is issued under the fixed designation D198; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu

2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONNumerous evaluations of structural members of solid sawn lumber have been conducted inaccordance with Test Methods D198 27. While the imp

3、ortance of continued use of a satisfactorystandard should not be underestimated, the original standard (1927) was designed primarily for sawnmaterial, such as solid wood bridge stringers and joists. With the advent of laminated timbers,wood-plywood composite members, and even reinforced and prestres

4、sed timbers, a procedureadaptable to a wider variety of wood structural members is required.The present standard expands the original standard to permit its application to wood members of alltypes. It provides methods of evaluation under loadings other than flexure in recognition of theincreasing ne

5、ed for improved knowledge of properties under such loadings as tension to reflect theincreasing use of dimensions lumber in the lower chords of trusses. The standard establishes practicesthat will permit correlation of results from different sources through the use of a uniform procedure.Provision i

6、s made for varying the procedure to take account of special problems.1. Scope1.1 These test methods cover the evaluation of lumber in structural size by various testing procedures.1.2 The test methods appear in the following order:SectionsFlexure 4 11Compression (Short Column) 13 20Compression (Long

7、 Member) 21 28Tension 29 36Torsion 37 44Shear Modulus 45 521.3 Notations and symbols relating to the various testing procedures are given in Appendix X1.1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units t

8、hat are provided for information only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the

9、 applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based ProductsD1165 Nomenclature of Commercial Hardwoods and SoftwoodsD2395 Test Methods for Specific Gravity of Wood and Wood-Based MaterialsD2915 Practice for Sa

10、mpling and Data-Analysis for Structural Wood and Wood-Based Products1 These test methods are under the jurisdiction ofASTM Committee D07 on Wood and are the direct responsibility of Subcommittee D07.01 on Fundamental Test Methodsand Properties.Current edition approved Sept. 1, 2009Oct. 1, 2013. Publ

11、ished September 2009October 2013. Originally approved in 1924. Last previous edition approved in 20082009as D198 08.D198 09. DOI: 10.1520/D0198-09.10.1520/D0198-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book

12、 of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technic

13、ally possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box

14、 C700, West Conshohocken, PA 19428-2959. United States1D3737 Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)D4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base MaterialsD4761 Test Methods for Mechanical Properties of Lumber a

15、nd Wood-Base Structural MaterialD7438 Practice for Field Calibration and Application of Hand-Held Moisture MetersE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Extensometer SystemsE177

16、 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE2309 Practices for Verification of Displacement Measuring Systems and Devices Used in Material Testing Machines3. Terminology3.1 Def

17、initions:3.1.1 See Terminology E6, Terminology D9, and Nomenclature D1165. A few related terms not covered in these standards areas follows:3.1.2 composite wood beama laminar construction comprising a combination of wood and other simple or complex materialsassembled and intimately fixed in relation

18、 to each other so as to use the properties of each to attain specific structural advantagefor the whole assembly.3.1.3 depth of beamthat dimension of the beam that is perpendicular to the span and parallel to the direction in which the loadis applied (Fig. 1).3.1.4 shear spantwo times the distance b

19、etween a reaction and the nearest load point for a symmetrically loaded beam (Fig.1).3.1.5 shear span-depth ratiothe numerical ratio of shear span divided by beam depth.3.1.6 spanthe total distance between reactions on which a beam is supported to accommodate a transverse load (Fig. 1).3.1.7 span-de

20、pth ratiothe numerical ratio of total span divided by beam depth.3.1.8 structural wood beamsolid wood, laminated wood, or composite structural members for which strength or stiffness, orboth are primary criteria for the intended application and which usually are used in full length and in cross-sect

21、ional sizes greaterthan nominal 2 by 2 in. (38 by 38 mm).FLEXURE4. Scope4.1 This test method covers the determination of the flexural properties of structural beams made of solid or laminated wood,or of composite constructions. This test method is intended primarily for beams of rectangular cross se

22、ction but is also applicableto beams of round and irregular shapes, such as round posts, I-beams, or other special sections.FIG. 1 Flexure Test MethodExample of Two-Point LoadingD198 1325. Summary of Test Method5.1 The structural member, usually a straight or a slightly cambered beam of rectangular

23、cross section, is subjected to a bendingmoment by supporting it near its ends, at locations called reactions, and applying transverse loads symmetrically imposed betweenthese reactions. The beam is deflected at a prescribed rate, and coordinate observations of loads and deflections are made untilrup

24、ture occurs.6. Significance and Use6.1 The flexural properties established by this test method provide:6.1.1 Data for use in development of grading rules and specifications;6.1.2 Data for use in development of working stresses for structural members;6.1.3 Data on the influence of imperfections on me

25、chanical properties of structural members;6.1.4 Data on strength properties of different species or grades in various structural sizes;6.1.5 Data for use in checking existing equations or hypotheses relating to the structural behavior of beams;6.1.6 Data on the effects of chemical or environmental c

26、onditions on mechanical properties;6.1.7 Data on effects of fabrication variables such as depth, taper, notches, or type of end joint in laminations; and6.1.8 Data on relationships between mechanical and physical properties.6.2 Procedures are described here in sufficient detail to permit duplication

27、 in different laboratories so that comparisons of resultsfrom different sources will be valid. Special circumstances may require deviation from some details of these procedures. Anyvariations shall be carefully described in the report (see Section 11).7. Apparatus7.1 Testing MachineAdevice that prov

28、ides (1) a rigid frame to support the specimen yet permit its deflection without restraint,(2) a loading head through which the force is applied without high-stress concentrations in the beam, and (3) a force-measuringdevice that is calibrated to ensure accuracy in accordance with Practices E4.7.2 S

29、upport ApparatusDevices that provide support of the specimen at the specified span.7.2.1 Reaction Bearing PlatesThe beam shall be supported by metal bearing plates to prevent damage to the beam at the pointof contact between beam and reaction support (Fig. 1). The plates shall be of sufficient lengt

30、h, thickness, and width to provide afirm bearing surface and ensure a uniform bearing stress across the width of the beam.7.2.2 Reaction SupportsThe bearing plates shall be supported by devices that provide unrestricted longitudinal deformationand rotation of the beam at the reactions due to loading

31、. Provisions shall be made to restrict horizontal translation of the beam (see7.3.1 and Appendix X5).7.2.3 Reaction Bearing Alignment Provisions shall be made at the reaction supports to allow for initial twist in the length ofthe beam. If the bearing surfaces of the beam at its reactions are not pa

32、rallel, the beam shall be shimmed or the individual bearingplates shall be rotated about an axis parallel to the span to provide full bearing across the width of the specimen. Supports withlateral self-alignment are normally used (Fig. 2).7.2.4 Lateral SupportSpecimens that have a depth-to-width rat

33、io of three or greater are subject to lateral instability duringloading, thus requiring lateral support. Support shall be provided at least at points located about halfway between a reaction anda load point. Additional supports may be used as required. Each support shall allow vertical movement with

34、out frictional restraintbut shall restrict lateral displacement (Fig. 3).7.3 Load ApparatusDevices that transfer load from the testing machine at designated points on the specimen. Provisions shallbe made to prevent eccentric loading of the load measuring device (see Appendix X5).7.3.1 Load Bearing

35、BlocksThe load shall be applied through bearing blocks (Fig. 1), which are of sufficient thickness andextending entirely across the beam width to eliminate high-stress concentrations at places of contact between beam and bearingblocks. Load shall be applied to the blocks in such a manner that the bl

36、ocks may rotate about an axis perpendicular to the span(Fig. 4). To prevent beam deflection without restraint in case of two-point loading, metal bearing plates and rollers shall be usedin conjunction with one or both load-bearing blocks, depending on the reaction support conditions (see Appendix X5

37、). Provisionssuch as rotatable bearings or shims shall be made to ensure full contact between the beam and the loading blocks. The size andshape of these loading blocks, plates, and rollers may vary with the size and shape of the beam, as well as for the reaction bearingplates and supports. For rect

38、angular beams, the loading surface of the blocks shall have a radius of curvature equal to two to fourtimes the beam depth. Beams having circular or irregular cross-sections shall have bearing blocks that distribute the load uniformlyto the bearing surface and permit unrestrained deflections.7.3.2 L

39、oad PointsLocation of load points relative to the reactions depends on the purpose of testing (see Appendix X5).7.3.2.1 Two-Point LoadingThe total load on the beam shall be applied equally at two points equidistant from the reactions.The two load points will normally be at a distance from their reac

40、tion equal to one third of the span (third-point loading), but forspecial purposes other distances may be specified.7.3.2.2 Center-Point LoadingIf required, a single load can be applied at mid-span.7.3.2.3 For evaluation of shear properties, center-point loading or two-point loading shall be used (s

41、ee Appendix X5).D198 1337.4 Deflection-Measuring Apparatus:7.4.1 GeneralFor modulus of elasticity calculations, devices shall be provided by which the deflection of the neutral axis ofthe beam at the center of the span is measured with respect to a straight line joining two reference points equidist

42、ant from thereactions and on the neutral axis of the beam.7.4.1.1 The apparent modulus of elasticity shall be calculated using the full-span deflection. The reference points for thefull-span deflection measurements shall be positioned such that a line perpendicular to the neutral axis at the locatio

43、n of thereference point, passes through the supports center of rotation.7.4.1.2 The true or shear-free modulus of elasticity shall be calculated using the shear-free deflection. The reference points forthe shear-free deflection measurements shall be positioned at cross-sections free of shear and str

44、ess concentrations (see AppendixX5).NOTE 1The apparent modulus of elasticity may be corrected for shear-corrected MOE calculations, assuming that the shear modulus is known. SeeAppendix X5.7.4.2 Wire DeflectometerDeflection may be read directly by means of a wire stretched taut between two nails dri

45、ven nails,smooth dowels, or other rounded fixtures attached to into the neutral axis of the beam directly above the reactions and extendingacross a scale attached at the neutral axis of the beam at midspan. Deflections may be read with a telescope or reading glass tomagnify the area where the wire c

46、rosses the scale. When a reading glass is used, a reflective surface placed adjacent to the scalewill help to avoid parallax.7.4.3 Yoke DeflectometerA satisfactory device commonly used for short, small beams or to measure deflection of the centerof the beam with respect to any point along the neutra

47、l axis consists of a lightweight U-shaped yoke suspended between nailsdriven into nails, smooth dowels, or other rounded fixtures attached to the beam at its neutral axis and a dial micrometer axis. Anelectronic displacement gauge, dial micrometer, or other suitable measurement device attached to th

48、e center of the yoke with itsstem attached to a nail driven into the beam at midspan at the neutral axis. Further modification of this device may be attained byreplacing the dial micrometer with a deflection transducer for automatic recording shall be used to measure vertical displacementat midspan

49、relative to the beam neutral axis (Fig. 4).7.4.4 Alternative DeflectometersDeflectometers that do not conform to the general requirements of 7.4.1 are permittedprovided the mean deflection measurements are not significantly different from those devices conforming to 7.4.1. The equivalencyof such devices to deflectometers, such as those described in 7.4.2 or 7.4.3, shall be documented and demonstrated by comparisontesting.NOTE 2Where possible, equivalency testing should be undertaken in the same type of product and stiffness range for whi